What is the ruling on the prayer of someone who suffers from flatulence during prayer, especially during prostration and bowing, and often does not feel it except at the beginning of prayer or when bending, and sometimes finds it difficult to ascertain that something has exited from him, with the repetition of ablution during Friday prayer?

There is no اعتبار (weight) given to doubt about the exit of something (from the body). If its exit is presumed, then the criterion for سلس (incontinence/continuous discharge) is that you do not find sufficient time to perform the prayer with a valid purification. If you find sufficient time, then pray within that time. If you do not find time, then perform ablution after the entry of the prayer time, and pray as much as you wish, and what exits from you after ablution will not harm you. Whoever experiences سلس while bowing or prostrating should bow and prostrate normally and not merely gesture for them.